Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 260954
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
454 AM CDT TUE APR 26 2016

.DISCUSSION...
THE STATE FALLING DOWNSTREAM OF AN UPPER LOW CURRENTLY LOCATED
OVER THE LOWER GREAT BASIN. LEEWARD ROCKY MOUNTAIN PRESSURES
FALLING WITH THE 995 MB SURFACE LOW CURRENTLY SITUATED OVER SW
KANSAS...DRY LINE EMANATING FROM THE TROUGH INTO THE PANHANDLE
AND SOUTHWARD INTO THE BIG BEND REGION. THE WARM FRONT EXTENDING
EASTWARD INTO THE CENTRAL PLAINS PLACING THE MAJORITY OF THE STATE
UNDER A WARM AIR ADVECTION FLOW PATTERN. A TIGHT ONSHORE PRESSURE
GRADIENT BACK TO THE 1016 MB FLORIDA-CENTRIC HIGH IS PRODUCING A
MODERATE SOUTHERLY WIND THAT HAS AIDED IN MAINTAINING AREAWIDE LOW
70 DEW POINTS. SOUTHEASTERN U.S. MID-LEVEL RIDGING AND ROCKY MOUNTAIN
LOW HAS PRODUCED AN ENTRENCHED SOUTHWEST WIND. THIS MID-LEVEL
STEERING FLOW HAS PULLED IN A WARM AIR MASS ALOFT...NOTED BY THE
8-9H LAYER CAPPING INVERSION IN BOTH LAST NIGHT`S CRP AND SHV
SOUNDINGS. THE EASTERN MOVEMENT OF THE GREAT BASIN 5H LOW INTO THE
(CENTRAL) WESTERN PLAINS WILL DRAW THE DRY LINE INTO CENTRAL
TEXAS TOMORROW MORNING. A QUASI-LINEAR CONVECTIVE LINE WILL LIKELY
DEVELOP ALONG THE DRY LINE THIS EVENING AND THIS LINE WILL PROPAGATE
EAST INTO NORTHEAST TEXAS THROUGH THE OVERNIGHT WEDNESDAY MORNING
HOURS. THE MODEL SUITE GENERALLY TRACKS THIS TSRA LINE INTO THE
NORTHERN FRINGES OF THE CWA BETWEEN 06 AND 12Z...BUT THE STRENGTH
OF THE DOWNSTREAM CAP WILL ULTIMATELY BECOME THE DECIDER. THE
TARGET COUNTIES FOR EITHER STRONG OR SEVERE STORMS WILL BE MADISON
...HOUSTON AND TRINITY AS THE CAP WILL LIKELY WEAKEN THE MOST
OVER THE NORTHEASTERN CWA. THE WRF-ARW DOES HOLD A QLCS TOGETHER...
POSSIBLY BOWING OUT EAST OF WACO/I-35 CORRIDOR AROUND MIDNIGHT.
THE HIGHEST CONFIDENCE LIES WITH A WEAKENING LINE THAT WILL TRAVEL
ACROSS THE FORECAST AREA FROM AS EARLY AS LATE TONIGHT THROUGH THE
EARLY AFTERNOON HOURS...THE BULK OF THE 1 TO 2 INCHES (LOCALLY 3
TO 4 INCHES) OF RAIN FALLING DURING THE EARLY MORNING HOURS. HIGH
MID-LEVEL LAPSE RATES EQUATING TO HIGH CAPE VALUES WITH HIGH LOW
LEVEL BULK SHEAR VALUES...ALONG WITH LOWER WBZ HEIGHTS...SUGGEST
THE MAIN THREATS WILL BE WIND AND HAIL. THE PROGRESSIVE NATURE OF
THE STORMS WILL MUTE THE HIGH RAINFALL THREAT. THERE IS DECENT
LOWER LEVEL VEERING (35-45 LLJ) OF WIND THAT DOES PRODUCE A HIGHER
SIGNAL FOR TORNADOES.

THURSDAY`S VACATING UPPER LOW INTO THE GREAT LAKES REGION WILL
QUICKLY BE FILLED BY THE NEXT IN-A-LINE OF UPPER LOWS. THIS LOW
IS CURRENTLY DIVING SOUTH OUT OF THE GULF OF ALASKA AND WILL DIG
DOWN INTO THE FOUR CORNERS REGION THROUGH LATE THURSDAY INTO EARLY
FRIDAY. THIS LOW IS CURRENTLY BEING MODELED TO TAKE A SIMILAR PATH
AS TOMORROW`S LOW...MAYBE A TOUCH MORE EAST THAN NORTH. THIS WILL
CREATE BETTER UPPER LEVEL DIFFULENCE OVER THE ARKLATEX REGION
(THAN TOMORROWW`S SYSTEM)...AND THIS COULD BE THE MARKER THAT
MAKES SATURDAY`S SYSTEM A POTENTIALLY STRONGER SYSTEM. BUT IN NOT
PUTTING THE CART BEFORE THE HORSE...PRECIPITATION CHANCES WILL BE
ON THE RISE FRIDAY WITH A TIGHTENED ONSHORE PRESSURE GRADIENT
PRODUCING A ROBUST 15-20 KT SOUTHERLY SURFACE WIND. HIGHER POCKETS
OF PVA AHEAD OF THE DESERT SOUTHWEST LOW SUGGEST THAT FRIDAY COULD
BE PLAGUED WITH PERIODS OF SCATTERED SHOWERS AND STORMS. THE ONE
INHIBITOR WOULD AGAIN BE THE STRENGTH OF THE MID-LEVEL WARM NOSE.
THE FORECAST CALLS FOR ANOTHER QLCS PASSAGE SATURDAY WITH PROFILES
DEPICTING WIND AND HIGH RAINFALL RATES AS POTENTIALLY HIGHER THREATS.

UNTIL A COLD FRONT SLATED FOR THE MONDAY-TUESDAY TIME FRAME COMES
THROUGH...PERSISTENT ONSHORE FLOW WILL ENSURE THIS MUGGY AND WARM
WEATHER PATTERN THROUGH THE REMAINDER OF THE MONTH. MORNING MINIMUM
TEMPERATURES WILL RANGE IN THE UPPER 60S TO LOWER 70S WITH DAYTIME
READINGS WARMING INTO THE AVERAGE MIDDLE 80S ON DAYS WHERE IS DOESN`T
RAIN...LOWER 80S ON THOSE DAYS IT RAINS DURING THE AFTERNOON. 31

&&

.MARINE...
MODERATE ONSHORE WINDS WILL CONTINUE THIS WEEK. THERE WILL LIKELY BE
INTERMITTENT FLUCTUATIONS WHEREAS CAUTION AND/OR ADVISORY FLAGS
WILL BE REQUIRED...THIS SHOULD BE ESPECIALLY TRUE LATER IN THE
WEEK AS THE PRESSURE GRADIENT FURTHER TIGHTENS AND THE FETCH
LENGTHENS. CORRESPONDING WIND SPEEDS AND SEAS WILL SEE A FURTHER
UPWARD BUMP GOING INTO THE WEEKEND. 47

&&

.AVIATION...
LOW LEVEL MOISTURE REMAINS TRAPPED BENEATH CAPPING INVERSION WHICH
SHOULD KEEP MVFR CIGS IN PLACE INTO AT LEAST THE MORNING HOURS.
THE NAM12 AND GFS DIFFER WITH REGARDS TO HOW QUICKLY HEATING WILL
MIX THINGS OUT. THE NAM12 KEEPS CIGS IN PLACE MOST OF THE DAY
WHILE THE GFS MIXES THINGS OUT AND ELIMINATES CIGS BY MID-MORNING.
CONTINUING TO LEAN TOWARD THE GFS SOLN FOR THE 12Z TAF PACKAGE.
SHOULD START SEEING SE WINDS BECOME GUSTY TOWARD MIDDAY AND
PERSIST THRU THE AFTN. COMPLEX OF TSTMS IS EXPECTED TO DEVELOP IN
N TX & OK LATER IN THE AFTN. TEMP INVERSION/CAPPING SHOULD LIMIT
SEVERE WX CHANCES LOCALLY...BUT TAIL END OF OF SOME OF THIS WEAKENING
PRECIP MAY MAKE ITS WAY INTO THE REGION LATE TONIGHT. THINK PREVIOUS
FCSTERS VCSH MENTION LOOKS GOOD AND WILL EXPAND A BIT SWD WITH
THIS PACKAGE. 47

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      87  69  84  67  86 /  10  60  30  10  20
HOUSTON (IAH)              85  72  85  71  86 /  10  50  50  10  20
GALVESTON (GLS)            82  73  79  74  82 /  10  20  50  20  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 10 AM CDT THIS MORNING
     FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY...
     WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO
     60 NM...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
     OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60
     NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.

&&

$$

DISCUSSION...31/47



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